Size classification of sutures



4 Sheets-Sheet l G. S. BOTT ET AL SIZE CLASSIFICATION OF SUTURES Sept.12, 1961 Filed Aug. 29, 1960 Sept. 12, 1961 G. s. BOTT ET AL sIzECLASSIFICATION oF sUIuREs 4 Sheets-Sheet 2 Filed Aug. 29, 1960 INVENTORSsfo/eef .fps/vcr@ @arr ATTURNEY m .MQ

ARTHUR s//vcLA/R TAYLOR BY Sept. 12, 1961 G. s. BOTT ETAI sIzI:CLASSIFICATION oF sUTUREs 4 Sheets-Sheet 3 Filed Aug. 29, 1960 INVENTORSGEoRGf SP5/vom orr ARTHUR s//vcLA/R TAYLOR ATTR/VEY SIZE CLASSIFICATIONOF SUTURES Filed Aug. 29, 1960 4 Sheets-Sheet 4 INVENTO 650/?65 SPENCERB T ARTHUR S//VCZA/R TAYLR BY A TTR/VE Y 7ment is described. groups,such that the minimum measured diameter at United States Patent() c anCyanamid Company, New York, N.Y., a corporation of Maine Filed Aug. 29,1960, Ser. No. 52,636 12 Claims. (Cl. 209-74) This invention relates toan apparatus and method for the rapid, automatic sorting of surgicalsutures, or other short lengths of strands or filaments, according totheir diameter. The sutures, or filaments, are kept straight and freefrom whipping by measuring While stretched between two sets of feedrolls, one of which acts as a drag, and when measured are transferred toa long, thin groove by vacuum, which groove has a removable dumpingseal.

In preparing surgical sutures, particularly from catgut,

that is, treated split animal membranes, frequently called gut, theproblem of size is important. The gut strands are formed by splittingvarious naturally occurring membranes into long, thin strings which aretwisted together and dried. These strands, which Will hereinafter becalled sutures, whether finished or unfinished, are necessarily somewhatuneven in diameter because the membranes are natural products and aresubject to biological uncertainties. In general, the twisting is sucientto insure that the cross section at any position is approximatelycircular so that any diameter measurement is suficient to establish thesize of the suture at that position. In the surgical eld, the suturesare classified into diameters according to various Governmentalstandards. In the United States, the standard is the United StatesPharmacopoeia. The maximum diameter at any position along the suturedetermines the size classification. For a homogeneous material, theminimum diameter determines the strength. inasmuch as it is desired tohave each suture as strong as possible within the diameter limits, it isdesirable to have a suture of uniform diameter so that the strength willbe uniform, and of a diameter which is as large as possible to remainwithin the size classification. i In the past, it has been customary togauge the sutures by hand, passing them over an anvil under themeasuring block of an indicator dial. The sutures have been hand sortedas to size, and then ground so that the dicmeter is uniform. ln eachinstance, the suture is placed in the group such that the largerdiameter sutures are reduced to not more than the measured minimum, andusually the suture is sufficiently ground that it is just within a sizeclassiiication. For instance, all sutures whose minimum diameter gaugesbetween the maximum fora size No. suture, 0.0195 inches, and 0.0230, themaximum for a size No. 1 suture, are ground to a uniform diameter justunder 0.0195 inches. Those with a minimum diameter over 0.0230 inches,are used for a size No. 1 or larger suture. Those with a minimumdiameter of less than 0.0195 inches are used for a size No. 00 orsmaller suture.

The measuring of a diameter at various positions along the length of thesuture by hand is a tedious and expensive operation.

We have now found it possible to mechanically, rapidly and accuratelyclassify the sutures into groups -based upon idiameter measurements. Itis obvious that the present apparatus could be adapted for classifyingby average or maximum diameters, but the usual desire is to classify bythe minimum diameter at any position along the length of the sutures andhence this preferred embodi- In general, the classilication is in twoer' 1C@ any position along the length of the suture is not less than thedesired diameter of the suture to be produced from the group, and theoversize is ground off in suture grinding machines. The grindingmachines are not part of the present invention.

In the classification of sutures by diameter, the sutures 1n general areof the order of live feet long. It is necessary to gauge each individualsuture separately for size classification. In the past, devices havebeen perfected for measuring continuous wires, for instance, a patent toG. E. Chilton et al., Continuous Reading Electronic Micrometer,2,850,645, September 2, 1958, describes one method of measuring therunning diameter of a wire. Some measuring devices incorporatingchoppers, which are suitable for measuring the diameters of continuousstrands, are disclosed in such patents as C. A. Vossberg et al.,2,548,755, Optical Area Measuring System, April 10, 1951. The apparatus,in general useful for measuring a continuous wire, is not satisfactoryfor measuring the diameter of sutures because the feed mechanisms topass the suture must be such that lengths of about tive feet can beconveniently measured, and the diameter measuring system mustdistinguish between the diameter being measured and the zero diameterwhich would be recorded in the interval between sutures.

ln feeding continuous wires, the problem of whipping is usually notparticularly serious because the position of the wire stabilizes after afew feet are fed. In feeding the lengths of sutures, it is necessarythat the position of the suture be stabilized to minimize whippingduring the measuring operation, and the actual measuring operation ispreferably such that a minor degree of whipping is not undulydeleterious, and does not give false measurements.

We have found that the sutures may be conveniently measured for size bypassing the sutures separately and sequentially through a guide tubeinto the bite of an en-- trance feed roll, through this feed roll, pastan optical measuring position to a faster feed roll; the drives beingarranged such that as soon as the faster feed rolls pick up the sutures,the suture is stretched to avoid whipping; and mechanically orelectrically the entrance feed roll is allowed to act as a drag on thesuture to keep it straight, but without permanently stretching thesuture; and the suture is propelled by the faster feed rolls to asorting mechanism which conveniently is a groove sut`n`ciently large toreceive the maximum size suture, in which vacuum applied to the groovedraws the suture into the groove. After the suture is completely gauged,and the entire length of the suture ylies within the groove, one side ofthe groove opens and dumps the sutures. Meanwhile, the diameter of thesuture at a plurality of positions is measured optically between the twosets of rolls, and the appropriate classification information is used toactuate bins or deflectors such that the suture, when dumped, falls intoa bin for sutures of that size. The size classication may beaccomplished by either an analog measurement in which the sutureinterrupts part of the light passing to a photodetector, and thereduction in incident light controls the size classification, ora yingspot scanner may be used in which the spot is interrupted by the suture,the peirod of interruption is as'- certained by a photodetector whichconverts the interruption to an electric signal, which signal isconverted to diameter information used to control the classifyingcircut. Conveniently, the period of spot interception can be used tocontrol gating circuits which pass a high frequency signal and, bycounting the number of cycles or' pulses passed, a digital measurementof diameter may be made. Such a digital measurement is frequentlyparticularly convenient because the stabilityof electric cir- 3 cuits ina digital system is less critical than in analog systems.

The above, and other objects, advantages and novel features of thepresent invention, which is defined in the appended claims, are betterunderstood in conjunction with the detailed description of certainembodiments of our invention which are set forth in greater detail inconjunction with the accompanying drawings in which:

FIGURE l is a diagrammatic view of a flying spot scanner, in conjunctionwith the suture feeding and sorting apparatus.

FIGURE 2 is a view of an analog gauging system in conjunction with thefeeding and sorting apparatus.

FIGURE 3 is a front view, in partial section, of the suture feed frameand gauging block assembly.

FIGURE 4 is a section along line 4 4 of FiGURE 3 showing the entrancefeed rolls.

FIGURE 5 is a section along line 5 5 of FIGURE 3 showing the insulated,mounted system for the guide idler roll.

FIGURE 6 is a view along line 6 6 of FIGURE 2 showing a deflection vanesorting system.

FIGURE 7 is a partial view in the same position as FIGURE 6 showing thedeflection vane sorting system in operation.

The apparatus has several sections that operate concurrently. Forconvenience in description, the feed section is described first,followed by the mechanical phase of the storage and dump sections, andthe bin selector, and then the descriptions of the optical systems andelectrical circuits in two alternate embodiments, a digital system andan analog gauging system.

The feed system is symbolically shown in FIGURES 1 and 2. The details ofthe suture feed subassembly are shown in Vl-:IGUBES 3, 4 and 5.

Suture feed T he suture feed system consists of a suture feed frame andgauge block 21 which acts as an electrical conductor for the ground sideof the circuits and supports the rolls. Mounted in the suture feed frameand gauge block is 'a fixed entrance feed roll 22, and along the path ofsuture travel a fixed guide roll 23, and a fixed faster feed roll 24.Each of these rolls is supported on fixed roll bearings 25. The mountingsystem for each of these three fixed rolls is the same. As shown inFIGURE 4 and as typical, the fixed entrance feed roll is mounted on thefixed entrance feed roll shaft 26, and consists of a conductive hub 27having an integral flange 28, on which is mounted a resilient annularcenter 29, which in turn is held in position by a retaining flange Sii.Each of the fixed rolls is ground to size so that the surfaces of theresilient annular center and the flanges are concentric and of the samediameter. The resilient annular center is preferably of a material suchas rubber or a plastic which has a high coefiicient of friction and thusprevents the suture from sliding. A polyurethane rubber is particularlysatisfactory as it has both a high coeicient of friction and anextremely tough surface which gives long Wearing life. On one end of thefixed entrance feed roll shaft 26 is a fixed entrance feed roll drivepulley 3l. Similarly positioned is a fixed guide roll drive pulley 32and a fixed faster feed roll drive pulley 33.

Above the respective fixed rolls is an entrance feed -idler roll 34, aguide idler roll 35, and a faster feed idler roll 36. These rolls aresubstantially the same, and are each mounted in an idler roll fork 37 onan idler roll shaft 38 which is supported in idler roll bearings 39.Each fork is mounted on a fork shaft 40 which is mounted Vin insulatingbushings 41, which bushings have shoul- ,ders to keep the fork centeredand to keep the fork in sulated from the suture feed frame and gaugeblock 2li. Each lfork is mounted so that it turns with the fork shaft.At one end of the fork shaft is mounted the idler fork shaft tension arm42, which is of an insulating material such as a fabric-reinforcedplastic, which arm is approximately parallel to the idler roll fork 37.A tension arm spring 43, in cooperation with a tension arm spring pin44, spring loads the idler roll fork so that each idler roll is pressedagainst its cooperating fixed roll. The fork shafts have at `their endan idler roll connector 45 to give an electrical contact through thefork to the respective idler rolls. The entrance feed roll lead 46 andthe faster feed roll lead 47 extend to the electrical circuits Whichactuate the start and finish of gauging operations and start the dumpingoperations, as later described. The surface of the respective idlerrolls is in contact with the metal flanges of the respective fixed rollswhen there is no suture 48 therebetween. As shown in FIGURE 4, thesuture 48 separates the respective pair of rolls as the suture is fedtherebetween breaking contact and giving electrical notice of thepresence of the suture.

The fixed entrance feed roll drive pulley 31 and fixed guide roll drivepulley 32 are driven by a first belt 49 which in turn is driven by adrag electric motor 50. A second belt 51, in turn driven by a principalelectric motor 52, drives the faster feed roll. Located in the samelongitudinal slot 53 in the suture feed frame and gauge block 21, as arethe respective roll pairs, are a group of suture guides. The suture 48is fed into a first suture guide 54 from which it is fed to the bite ofthe entrance feed rolls. As the suture emerges frorn the cntrance feedrolls, the suture is picked up and directed by a second suture guide 5S,which directs the suture to the guide roll pair. As the suture emergesfrom the guide roll pair, it is picked up by a third suture guide 56which controls its path as it enters the gauging Zone 57. The gaugingzone 57 is a cross slot in the suture feed frame and gauge block throughwhich the light bearns of the gauging system operate, as describedbelow. As the suture emerges from the gauging zone, it is picked up by afourth suture guide S8 which directs it to the bite Yof the faster feedroll pair from which it is picked up by the fifth suture guide 59, fromwhich it is directed towards a transfer and/ or sorting system,described below. Each of the suture guides has a conical entrance 6()and a directing bore 61. The conical entrance is big enough that thesuture is easily directed into the conical entrance, and the conicalentrance guides its path to the directing bore. The directing bore ispreferably just larger than the largest diameter of the largest suture,which may be fed into the system, so that the suture 1s directed with aminimum of whipping or lost motion along its path to the next workingposition.

Operation of suture feed A suture is fed into the conical entrance o fthe first suture guide which `directs it towards the entrance feedrolls. Once the end of the suture is fed into the bite or nip of theseentrance feed rolls, the suture is mechanically propelled and may bereleased by the operator who is then free to select the next suture tobe engaged. A s the suture emerges from the entrance feed rolls, it isdirected through the second suture guide to the guide rolls, and by themthrough the third suture gauge to the gauging zone, in which theopt-ical gauging occurs. From this gauging zone, the suture is directedthrough the fourth suture guide and into the bite of the faster feedrolls.

The faster feed rolls are driven at 'a surface speed preferably of about5% to 10% greater than the surface speed of the entrance feed rolls andthe guide rolls. The suture is thus picked up and accelerated by thefaster feed rolls, which immediately removes any slack in Vthe suturebetween the faster feed rolls and the guide rolls and entrance feedrolls. rl`he guide feed rolls and entrance feed rolls `are driven by `acommon drag electric motor 5t) and have the sarne surface speed.Whereas, it would be possible to adjust the spring loading so as topermit the rolls to slide on the suture when the speeds are notidentical, Such sliding would cause rapid wear pa D fof ythe resilientannular centers and would tend to coil-y tribute to a lateral whippingaction of the suture. It is therefore preferred that the drag electricmotor be an induction-type motor which can be accelerated by the tensionon the suture so that as soon as the principal electric motor 52 takesover control of the feed motion of the suture, the drag electric motorno longer acts to propel, but thus acts to drag on the suture, thuskeeping the suture straight and reducing whipping. It is acharacteristic of an induction motor that the rotor lags behind itsinductive field when operating as a motor. As the rotor of `the dragelectric motor is speeded up, the current consumption drops and therotor begins to gain on its magnetic field. Actually, the rotor can beoverspeeded so that it is driven faster than its magnetic field, inwhich case the motor functions as a generator. If both the principalelectric motor and the drag electric motor are small induction motorswith a comparatively high slippage, as is usually common in smallinduction motors, the drag on the drag motor straightens out the suturewhile the inertia of the system is small enough not to unduly jar smoothconveyance. The principal electric motor has an increased slippage, andthe drag motor a reduced slippage.

The breaking of contact between the faster feed rolls acts to start agauging operation, which operation is electrically delayed enough thatthe suture is drawn tight before the ilrst effective diametermeasurements are made. The contacting of the faster feed rolls andclosing of the circuit between them also actuates the bin selectorsystem. The initial breaking of contact as the suture is feed into theentrance feed rolls is normally not used as a signal, but the closing ofthe entrance feed rolls and the establishing of contact is used to closethe diameter memory latches, transfer the stored information as todiameter size to a bin selector control, and then reset the memory latchsystem. inasmuch as the end of the suture starts to whip as soon as itpasses the entrance feed rolls, the guide feed rolls are interposed tocontrol the path of the suture and prevent any whipping from occurringuntil after the memory system is closed, so that erroneous diametermeasurements, which might be induced by the free end of the suturewhipping as it passes through the gauging zone, have no effect on theclassication.

Storage, bin Selection and dump 4chamber 62 has a vacuum bleed 63 whichreduces the pressure at the discharge end of the holding chamber. Theair flowing through the holding chamber picks up the suture as itemerges from the fifth suture guide and draws it into the storagechamber.

The function of the storage chamber is to permit accelerated operation.The gauging operation itself is comparatively slow and may require fromabout one to four seconds for a five-foot length of suture. The dumpingoperation, later described, is also comparatively slow. It may require asecond or two for dumping to occur, and the dumper to be reset toreceive the next suture. If the dumping system is placed right next tothe fifth suture guide, it is necessary to wait until one suture hascleared the dumping operation and the receiving groove is reset beforethe next suture may be fed. To expedite operations, the holding chamberis interposed. The holding chamber is long enough to hold a suture andthe suture is fed into the holding chamber and is stored there untilgauging is completed. At this time, the 'suture is ready for immediatetransfer to the groove in the dumping mechanism and is rapidly drawn, inva fraction of a second, into the groove which frees the holding chamberfor a following suture and the dumping mechanism dumps one sutureconcurrently with the gauging of the following suture. By thus having aholding chamber which permits a fast transfer, the two comparativelyslow operations of gauging and dumping do not delay one another.

The comparative length of the holding chamber and the dumping mechanismin FIGURE 2 is markedly reduced as is illustrated by the broken lines,inasmuch as the holding chamber must be long enough to receive thelongest suture to be gauged, normally about six feet, and preferably hasa diameter not greatly in excess of the largest diameter of the largestsuture to be gauged, which may be as much as about 1/16 of an inch. Ifin correct proportion without a break, the diameter would be so slightas to obscure detail.

As shown in FIGURES 2, 6, and 7, the sutures are sorted into a group ofbins. Although the number of bins which `are selected varies with thesize variation in the fed stock, for purposes of convenience the presentinvention is illustrated as classifying the sutures into five groups.These are designated as a bin for size #1, 64, a bin for size #2, 65, abin for size #3, 66, a bin for size #4, 67, and a bin for oversize, `68.The bins are arranged with sizes #l and #2 on one side, sizes #3 and #4on the other side, and the oversize bin at the bottom of a suture droppathway 69. Adjacent to ythe suture drop pathway are a plurality ofdeflection vanes, one for each of the four suture sizes, a size #ldeflection vane, 7), a size #2 deflection vane, 71, a size #3 deilectionvane, 72, and a size #4, deflection vane, 73. The deflection vanes `arerotatably pivoted and swing from a vertical inactive position to asloped active position. The pivoting of the vanes is controlled by vanesolenoids 74, one for each deflection Vane. The vanes are biased back toa vertical position by vane springs 75. The proper solenoid is selectedby the bin selector control described further in connection with theelectrical circuits `according to size data from the gauge system. Asshown in FIGURE 7, in the dumping operation the suture is deflected byone of the deflection vanes to the proper one of the bins for sizes #1,#2, #3 or #4. If the suture is not of such size that the suture belongsin one of these four classes, but instead is oversized, none of thevanes are actuated, and the suture falls through the suture drop pathway69 between the vanes and into the bin for oversized sutures 68.

Above the suture drop pathway is the dumper. The dumper consists of agrooved rotatable -bar 76? having a rectangular groove 77 therein. Inthe suture loading position, the rectangular groove faces and is closedby a rubber-faced rotatable bar 78. These two bars are stiff enough toavoid undue flexure or are positioned by suitable clamp rolls so that inthe `suture loading position, shown in FIGURE 6, the rectangular groove77 is sealed by the rubber-faced rotatable bar, with the groove end opentowards the holding chamber 62 and is in align- Yment therewith. Agroove vacuum line 79 adjacent the second and closed end of the grooveacts through an air exhaust port and reduces the pressure in the -groovenear the end opposed to the holding chamber. Thus, a suture in theholding chamber is drawn by the groove vacuum into the groove. Thegroove vacuum line should have a higher vacuum than the vacuum bleed 63so that a suture is drawn from the holding chamber 62 into the groove bythe vacuum acting through the groove vacuum line 79, which effectivelyoverpowers the effect of the vacuum bleed to the holding chamber. Ascreen or foraminous area may be used to prevent the end of the suturebeing drawn into the vacuum line. The grooved rotatable bar and therubber-faced rotatable bar are connected together by a drive gear 80 anda driven gear 81. An air cylinder 82 is mounted to rotate the groovedrotatable bar 7 6 through a rotating linkage 83. The air cylinder iscontrolled by the bin selector control and at the appropriate time airis admitted to the air cylinder which rotates the grooved rotatable bar,and through the drive gear and the driven gear also rotates therubber-faced rotatable bar. As Ythe two bars rotate, the vacuum isbroken, and the rectangular groove 77 is rotated downward so that asuture 48, therein, is dumped out of the groove and down towards thesuture drop pathway. The suture falls into the oversize bin unless oneof the deflection vanes deiiects the suture into a bin for sutures of anappropriate size.

The bin selector `control system is described below.

The suture is automatically drawn from the holding chamber 62 as therotatable grooved bar realigns the groove 77 with the end of the holdingchamber 62, hence, no special operation is required. If the gaugingoperation is not complete, the suture is not released from the fasterfeed rolls and, accordingly, the bin selector control is not actuatedand the dumping system remains inactive until gauging is completed.

For small sized sutures, which may not fall out of the groove suicientlyrapidly, an air line 84 is provided with an opening into the groove, andmechanically or electrically after the grooved rotatable ba-r hasrotated to dumping position, a short air blast is fed through the airline to assist in disengaging the suture. Usually, such auxiliarydumping air is not required.

Digital classification A block digital classification electrical circuitis shown in FIGURE l. The flying spot scanner may use a iiying spotelectrically scanned on the face of a `cathode ray tube, or a flyingspot produced by a multiple-sided rotating mirror. Conveniently, thesuture is gauged in a. horizontal position so that the scanning spotmoves vertically. An image of the flying spot is formed by :a focusinglens 85 on the suture 48 in the gauging zone 57. Preferably, the lightfrom the spot has substantially parallel rays and is in sharp focus asit passes the suture. The light which passes the suture is picked up bya collector lens 86 and forms an image on a photoelectric device,preferably a photomultiplier tube. The output of this photomultiplierthus shows as an electrical signal Whether the spot is passing or isintercepted by the suture. The size of the spot in the gauging zoneshould be small as compared with the `size of the suture so that theelectrical output from the photomultiplier will be a comparativelysharp-edged signal. The number of scans per second is such that thesuture is gauged by a scan at appropriate longitudinal positions. If thespot moves `at a frequency of 500 scans per second, the suture can moveat a speed of 50 inches per second and still give `a scan signal eve-rytenth of an inch of length.

The scan signal passes to an amplifier, shaper and differentiator wherethe scan signal is amplified, extraneous noise and false signals due tothe spot passing the edge of the gauging zone removed, and the signalsplit into a leading edge signal corresponding to the spot lirstcontacting the suture, and a trailing edge latch signal, correspondingto the suture just clearing the edge of the spot. These two signals arespaced apart in time proportional to the width of the suture, with duereference to the rate of scan.

As shown in `FIGURE l, there are four different size control systems forthe four different sizes of bins. For purposes of convenience, only onewill be described, the others operating identically. A preciseoscillator generates an electrical signal consisting of a number ofelectrical signals or pulses. A 1,000' kilocycle, crystalcontrolledoscillator gives good results. The pulses are passed to pulse gate #lwhich may 4be a conventional pentode in which the pulses are passed tothe signal grid. The leading edge signal, conveniently through amultivibrator, is connected to the control grid, usually the third gridof the pentode. Thus, the leading edge signal opens the gate. The pulsespass through the pulse gate to a preset counter which is set to beactuated at the end of a certain number of pulses, which number isadjusted te sensation@ t the size information desired* Thus,

if the flying spot moves across the suture at a speed of L00 inches persecond, each pulse from a l megacycle oscillator ywould correspond to adimension of one 10,000th of an inch and a count of would be set todistinguish sutures which had a minimum diameter of 0.0195 inch, whichcorresponds to a size No. 0 suture. At the end of the count, the countergives a count completed signal which is used to close the pulse gate andreset thecounter. A set of three 6,70() magnetic beam switching tubesmay be used as the counters, or any conventional electronic countersystem may be used. The leading edge signal and the output signal fromthe counter are also used to open and close the signal gate whichelectrically is parallel with the pulse gate, and is open for the samelength of time.

The trailing edge latch signal from the ampliiier, shaper anddiiferentiator is directed to the signal gate. if the suture is smallerthan the preset size, the trailing edge signal hits the signal gatebefore the gate is closed. lf the diameter of the suture is larger thanthe preset size, the signal gate is closed before the trailing edgelatch signal arrives and hence the signal does not pass the gate. Thus,the output from the signal gate indicates that a particular diameter issmaller than a preset size.

This information is fed to the memory and latch #1. This conveniently isa thyratron tube. The thyratron may be controlled by a relay opening itscathode return. The cathode return is open until the suture opens thefaster feed roll pair 24 and 36 as previously mentioned. The relayconveniently uses an electronic circuit so a very small current throughthe rolls can be used. The relay should be slow enough in operation topermit the suture to `be stretched before the cathode return is closed.An ordinary magnetic relay is satisfactory. When the suture breaks theconnection between these rolls, the memory start signal operates therelay to close the cathode return and any signal which passes the signalgate to the memory latch tires the thyratron. Once the thyratron isfired, it remains conductive until the cathode circuit is opened andthus the thyratron memory retains or remembers that the suture in oneposition has a diameter of less than the set size.

Each memory and latch #1, #2, #3 and #4, stores the data for a differentsuture size.

When the end of the suture passes the entrance feed rolls 22 and 34, asignal is given which closes the memory circuit, and first transfersinformation as to which thyratrons have been tired to the bin selectorcontrol, and then opens the cathode return to reset the thyratrons. The`bin selector control is conveniently a group of relays which arearranged to each inactivate the relays for any larger sizeclassification, and the smallest size classificam tion relay alsooperates the bin selector `which starts to operate as soon as the end ofthe suture passes the faster feed rolls 24 and 36, and which binselector activatesy the appropriate deflector vane for the size asmeasured and simultaneously activates the air cylinder 82 which startsthe rotation of the grooved rotatable bar and the dumping of the suture.The appropriate vane thus deflects tbe suture into bips #1 #2, #I3V or#4, or if none of the memory and latches have been activated all vanesremain stationary and the suture falls into the oversize bin. Themechanical `delay inherent in the relays and air cylinder V82 issufiicient for the suture to be transferred to the groove 77 before thebars start to rotate.

Although the particular description is in connection with certain typesof pulse gates, signal gates and preset counters, it is to be understoodthat appropriate transistor circuits or other types of counters andcircuits may be used to correlate the information from the ying spot ttoactuate the bin selector to cause the dumping of the suture into anappropriate bin. Signal lights are also connected to the bin selectorcontrol to indicate visually the size ot each suture.

Analog classification A11 analog classifier is shown in FIGURE 2.

The digital classifier has the advantage of using a precise oscillatoras the circuit control, and the ying spot, through the photornultiplier,gives only an off-andon signal corresponding to the interception of theiiying spot by the suture. The size is indicated as a function of thenumber of pulses. `Such a system is :largely independent of circuitvariations and, accordingly, a considerable variation in any of thecircuit values with time, temperature or supply voltage, such as in aresistor or a condenser or the amplification of a tube does not have anadverse effect on ythe size classification. By the same token, thecircuits are comparatively complex.

A11 analog system has the advantage of greater simplicity, but with thedisadvantages that the system is more subject .to `drift from aging,voltage variations and temperature variations as the size of a signal isthe controlling factor. With voltage control on the electric circuitsand a temperature-controlled room, and using highgrade components whichare comparatively free from drift, an analog classifier has theadvantages of simplicity and ease of checking. The feeding and dumpingmay be the same as with the digital device previously described.

On one side of the gauging zone 57 is mounted a lamp 87, as a lightsource, the light from which passes through a collimator lens 88 whichfocuses the light passing to give parallel light rays and uniformillumination on two slits.

The slits are mounted on the other side of the suture path. In theoptical gauge plate 89 is a reference slit 90. This reference slit is ofstandard size and is used as a basis for comparison. Behind the sutureis an adjustable measuring slit 91. The width of the adjustablemeasuring slit is controlled by a micrometer spindle 92 `Which moves ablade 93 which opens and closes the ad- ,justable measuring slit. Adouble lens 94 focuses the light passing each slit on its own photocell.The reference photocell 95 receives the beam through the reference slitand ther measuring photocell 96 receives the beam through the adjustablemeasuring slit. The relative intensity of the light on the referencephotocell and 'the measuring photocell controls the gauging. Thereference photocell serves as a null value giving compensation forvariation in lamp characteristics, Voltage sup- Vply and/or othervariables. The difference signal amplitude is a function of suture size,and controls the sorting systems.

One convenient system of utilizing the signals from the photocellsincludes feeding the signals from each to the respective grids of anamplifier, conveniently a twin tri- "ode such as a 6SN7, which can bewired with a corn- Ymon plate potential and duplicate grid resistors ofabout f5.6' megohrns and with condensers to the cathodes to "blank outhigh frequency variations.

The cathodes can be connected through cathode return resistors to groundlof about 560 kilohms, and the cathodes wired to the grids Aof a secondstage, conveniently also a 6SN7, with separate cathode resistors ofabout 1,500 ohms. As so wired,

by using matched components the photocell output from cells such as aCE34Q, or other photocells, lare suiciently amplified to be easilymeasured. Conveniently, a meter may be wired across the two cathodes andcali- .brated to give an absolute size measurement as a readout monitor.For automatic sorting, the cathodes are .connected together through aresistor and twin diodes,

.10 `difference in the cathode potentials and in one direc.- tion only.Such a parametric amplier is a particularly convenient method ofconverting a D.C. signal to an A.C. signal. As is well known,amplification is easier with A.C. signals and drift problems arereduced. The parametrically clamped square wave signal can be used tofeed a group of variable amplification stages which each control athyratron. The amplifier for each thyratron is set by controlling itsamplification so that the thyratron fires at a signal corresponding to adesired size. Thus, the signal system is individually calibrated. Themeter across the cathodes of the second amplifier serves as a readoutmonitor to inform the operator of the size of the suture at each andevery position along its length. An ordinary DArsonval meter respondssufficiently rapidly for most purposes. A cathode ray oscilloscope canbe used for faster response. The memory and latches and bin selectorsystems are conveniently essentially the same as described in connectionwith the digital classifier, although as shown in FIGURE 2 the memoryclose, transfer and reset are actuated by the entrance feed roll, withthe electric circuits providing for suicient delay that the transfer,dumping, and vane actuation, occur in proper sequence.

In operation, after the analog system has had an opportunity to warm upand stabilize, the micrometer slit adjustment is closed until thereference photocell and measuring photocell balance. This is taken as azero point. The slit is then opened a distance corresponding to thefirst minimum diameter measurement, andthe amplifier to the first memorythyratron is set to fire the thyratron yat this value. The slit is thenopened to the second minimum size value, and the second thyratron set tofire. This sequence is followed for each thyratron. Wires of known sizecan be placed by hand in the feed system to check the uniformity ofresponse. The monitor meter may have a shunt or series resistor to con-Atrol its sensitivity or provide calibration. In use from time to time,the drift 0f the circuits can be checked by resetting the micrometerslit adjustment to appropriate values to see if the thyratrons stillfire at the desired values.

It is frequently convenient to include signal lights in parallel withthe bin selector controls so that the operator can see the sizeindicated for each suture. If desired, counters can be installed withthe signal lights to count the number of sutures which are sorted intoeach bin.

As is obvious to those skilled in the art, the exact construction shownis exemplary rather than definitive. For example, the bins themselvesmay be moved instead of the vanes. The number of classified sizes may bechosen for particular operations. Should it be desirable, the sutures orother strands could be classified by maximum rather than minimum sizes.Additionally, transistor or other circuits may be used. If sufficientlystable circuits are chosen, but a single light beam may "be used in' ananalog system. Two pair of rolls can be used if the memory circuits arevery rapidly closed after the end of the suture passes the entrance feedrolls, and before the suture has time to whip. Other modifications andvariations within the scope of the appended claims are part of thepresen-t invention.

We claim:

l. Apparatus for classifying sutures according to predetermined diameterclassification limits which comprises, in combination: guide .means tocontrol the path of a suture, at least a pair of entrance feed rolls anda pair lof faster feed rolls, the rolls of each pair having parallelaxes, and having at least a circular part of each of the four rolls ofan electrically conductive material, means to hold each pair of rolls injuxtaposition under sufficient loading to be in electrical contact whenthe rolls of the pair are not separated by a suture between them, thesaid pairs of rolls being mounted with all rolls tangent to the annessePth f the suture, means to determine when each pair of rolls is inelectrical contact and when each pair of rolls is separated by a suture,means to drivcthe entrance feed rolls, means to drive the faster feedrolls at a faster surface speed than the driven speed of the en trancefeed rolls and to thereby keep the suture stretched while between thetwo pair of rolls, at least one of said drive means permitting slippagewith respect to the suture; a gauging zone between the entrance feedrolls and the faster feed rolls, gauging means functioning through saidgauging zone; a holding chamber, said guide means being coaxial with andserving to direct the suture into the holding chamber after the suturehas passed the said rolls and gauging Zone; a rotatable bar having agroove therein parallel to the axis of the bar, a resilient facedrotatable bar parallel and adjacent to and in sealing engagement withsaid grooved bar and sealing the groove when said groove is in asuture-receiving position, when in said suture-receiving position saidgroove being coaxial with said holding chamber and in position toreceive a suture therefrom, a plurality of suture bins, and meanscontrolled by the gauging means and the electric contact between therolls of each pair of rolls to disengage the groove from engagement withthe resilient faced bar, and to dump the suture from the groove, andmeans controlled by the gauging means to direct the suture into a suturebin selected on the basis of the gauged size characteristics of thesuture.

2. In an apparatus for classifying sutures according to predetermineddiameter classification limits which comprises, in combination: guidemeans to control the path of a suture, and direct it to at least a pairof entrance feed rolls and a pair of faster feed rolls, the rolls ofeach pair having parallel axes, means to sense when a suture is betweenthe rolls, means to drive the entrance feed rolls, means to drive thefaster feed rolls at a faster surface speed, to thereby keep the suturestretched while between the two pair of rolls;- a gauging zone betweenthe entrance feed rolls and the faster feed rolls, gauging meansfunctioning through said gauging zone to determine size characteristicsof a suture;V a dumping means having a groove parallel to the axis ofthe suture travel, and coaxial therewith, to receive a suture; suturebins; means controlled by the gauging means and electric contact betweenthe rolls of each pair to actuate the dumping of a suture from thegroove, and means controlled by the gauging means to direct the sutureinto a suture bin selected on the basis of the gauged size characterisutics of the suture.

3. In an apparatus for classifying sutures into groups based on theminimum of many single diameter measurements at a plurality of positionsalong the axis of the suture, the improvement comprising: a pair ofentrance feed rolls, a pair of guide rolls, and a pair ofY faster feedrolls, the axes of both rolls of all pairs being parallel, each of theentrance feed rolls and faster feed roll, pair comprising a driving rollhaving electrically conductive fianges and a resilient annular center ofa lcomposition having a high coefficient of friction with a suture, andan idler roll having at least the part contacting said fianges of anelectrically conductive material, resilient means to press the rolls ofall pairs towards each other, with part of the gap between the guiderolls and the faster feed rolls forming a gauging zone; a first sutureguide to` direct a suture towards the bite of the entrance feed rolls, asecond suture guide to receive the suture from the entrance feed rollsand direct the suture towards the guide rolls, a third suture guide toreceive the suture from the guide rolls and direct the suture towardsand control the suture path approaching the gauging zone, a fourthsuture guide to receive the suture from the gauging zone and direct thesuture towards the faster feed rolls, and a fifth suture guide toreceive the suture from the faster feed rolls, and direct the suturetowards a suture sorting means; a gauging means functioning through saidgauging zone; means for passing a first electric current through theentrance feed rolls, which first current is interrupted `by the passageof a suture, means for passing a second electric current through thefaster feed rolls, which second current is interrupted by the passage ofa suture, means to limit the effective operation of the gauging means tothat time when both said electric currents are interrupted by a suture;means to drive the entrance feed rolls and the guide rolls, includingmeans to drive the faster feed rolls at a faster surface speed than theentrance feed rolls, and to permit slippage in the drive means tothereby keep the suture stretched while between the entrance feed nollsand the faster feed rolls; and means to receive the suture from saidfifth suture guide, and means to direct the suture into a size bin basedon intelligence from said gauging means.

4. An apparatus for classifying sutures into size groups based on singlediameter measurements at a plurality of positions along the axis of thesuture, -the improvement comprising: a pair of entrance feed rolls, anda pair of faster feed rolls, the axes of all rolls being parallel, meansto press the rolls of both pair towards each other, part of the gapbetween the entrance feed rolls and the faster feed rolls forming agauging Zone; suture guide means to direct a suture towards the bite ofthe entrance feed rolls, thence through the gauging zone, the fasterfeed rolls, and then towards a suture sorting means, a gauging meansfunctioning through said gauging zone, means to determine when both pairof feed rolls have a suture between them; means to limit the effectiveoperation of the gauging means to that time when a suture is betweenboth pair of rolls; means to drive the entrance feed rolls, means todrive the faster feed rolls at a faster surface speed than the entrancefeed rolls, and to permit slippage to thereby keep the suture stretchedwhile between the entrance feed rolls and the faster feed rolls, meansto receive the suture from said suture guide means, and means to directthe suture into a size bin based on i11- telligence from saidl gaugingmeans.

5. In an apparatus for classifying sutures into size groups, theimprovement comprising: a pair of entrance feed rolls, and a pair offaster feed rolls, the axes of all rolls being parallel, means to pressthe rolls of each pair towards each other, part of the gap between theguide rolls and the faster feed rolls forming a gauging zone, sutureguide means to direct a suture towards the bite of the entrance feedrolls, thence through theV gaug- -ing zone, the faster feed rolls andthen towards a suture sorting means, a gauging means functioning throughsaid gauge zone, means to determine when both pair of feed rolls have asuture between them, means to limit the effective operation of thegauging means to that time when a suture is between both pair of rolls;and means to drive the entrance feed rolls and the faster feed rolls atsuch relative speeds that a suture between them is kept stretched enoughto avoid whipping.

6. An apparatus for classifying sutures according to predetermineddiameter measurements, which comprises: three pairs of rolls having aperipheral portion of metal, the rolls of each pair being held injuxtaposition to one another under sufficient loading to make electricalcontact when no suture is therebetween, but insuficient to block theirseparation by a suture passing between them, the said pairs of rollsbeing mounted in a support so that the points of contact between therolls of each pair all fall in a line, the said pairs of rolls beingcooperatively rotated mechanically so that respective tangential edgesof each roll of said pairs and of each pa-ir in respect to the othermove in the same direction, an optical scanning means positioned to scancontinuously a zone between the second and third of said pairs of rollsand designed to issue after a suture has beenY scanned one of a seriesof electrical signals corresponding to a predetermined series of limitsin the diameter 0fv the said suture, the first two of` said pairs ofrolls acting to feed a length of suture into said zone and the thirdpair of rolls acting to withdraw it from said zone, the said third pairof rolls having a greater peripheral velocity than the said rst twopairs; two rotatable parallel tangentially contacting cylinders, one ofwhich has a slot along the line of tangency, which is closed by theother cylinder when in the suture-receiving position, the said cylindersbeing positioned with the said slot lying along the line joining thepoint of tangency of the three said pairs of rolls, a series of storagebins corresponding to said predetermined series of limits and rigidlymounted such that one is directly below said cylinders and the othersare below and to one or the other side of said cylinders, a series oflong, independently rotatable vanes corresponding to said side binsmounted below the said rotatable cylinders in such fashion that in thenormal vertical position of said vanes there is an unobstructed dropfrom said cylinders to said lower bin, each of said vanes when in yarotated position diverting the drop of a suture to the bin to which itcorresponds, means for rotating said cylinders to a position wherein thesaid longitudinal slot is exposed over the said drop, means for rotatingsaid vanes individually to obstruct, and divert the suture drop uponactuation by the said signal from said scanning means, in correspondenceto size intelligence, the said means for rotating said cylinders beingactuated by the electrical contacts formed by the closing of said rolls.

7. An alternatively vacuum loaded and pressure ejection mechanism forsutures which comprises a pair of solid parallel rotatable cylinderstouching along one side; the first of said cylinders having alongitudinal slot down the line of tangency, the said longitudinal slotbeing open at one end and having an air exhaust port at the other; aresilient coating around the arc of tangency of the second of saidcylinders such that in the normal position when the said slot is at thepoint of tangency said resilient material forms an air-tight seal alongthe length of the said slot, means for partially rotating said cylinderscooperatively so as to expose said slot and discharge a suturetherefrom, and means for exhausting a-ir through said exhaust port whensaid slot is in the normal position.

8. An alternatively vacuum loaded and pressure ejection mechanism forsutures which comprises a pair of solid parallel rotatable cylinderstouching along one side; the rst of said cylinders having a longitudinalslot down the line of tangency, the said longitudinal slot being open atone end and having an air exhaust port at the other; a resilient coatingaround the arc of tangency of the second of said cylinders such that inthe normal position when the said slot is at the point of tangency, saidresilient material forms an air-tight seal along the length of the saidslot, means for partially rotating said cylinders cooperatively so as toexpose said slot and discharge a suture therefrom, and means forexhausting air through said exhaust port when said slot is in the normalposition, and means for applying air pressure into said slot when saidcylinders are in the rotated position.

9. In an apparatus for classifying sutures, the improvement in dumpingmeans which comprises: a bar having therein a long, thin groove havingone open end and an open face, means to seal the open face of the groovewhen the bar is in a loading position, means to change the position ofsaid bar with respect to said seal means to a discharge position inwhich discharge position the contents of the groove are released,evacuating means adjacent the second and closed end of the groove todraw a suture into the groove when the groove is closed, and a guidemeans adjacent to and coaxial with said one open end of said groove todirect a suture axially into the groove.

l0. In an apparatus for classifying sutures, the provement in dumpingmeans which comprises: a rotatable bar having therein a long, thingroove having one open end and an open face, a second parallel rotatablebar to seal the open face of the groove when the bar is in a loadingposition, resilient seal means between said bars, means to move saidrotatable bar relative to said second bar to a discharge position, inwhich discharge position the contents of the groove are released,evacuating means adjacent the second and closed end of the groove todraw a suture into the groove when the groove is closed, and a guidemeans adjacent to and coaxial with said one open end of said groove todirect a suture axially into the groove.

1l. A method of classifying sutures into groups based upon the minimumdiameter at any position along the strand, based upon single diametermeasurements at a plurality of positions along the axis of the suturewhich comprises: feeding each suture axially along a limited path, pastan optical diameter sensing position, optically sensing the suturediameter repeatedly, sensing the presence of the suture in said pathbefore and after the diameter sensing position, maintaining the suturein tension to reduce whip between said suture sensing positions,utilizing only those measurements which are taken while the presence ofthe suture is sensed both ahead of and behind the diameter sensingposition, determining the minimum of all utilized diameter measurements,moving the suture to a storage position by reducing the pressure in adumping position and thereby transferring the suture from storageposition to dumping position, discharging the suture from the dumpingposition, and passing the suture along a path controlled by the saidminimum diameter measurement to a bin appropriate to said minimummeasurement.

12. A method of classifying sutures into groups based upon the minimumdiameter at any position along the strand, based upon single diametermeasurements at a plurality of positions along the axis of the suturewhich comprises: feeding each suture axially along the limited path,past a diameter sensing position, sensing the suture diameterrepeatedly, sensing the presence of the suture in said path before andafter the diameter sensing position, maintaining the suture in tensionto reduce whip between said suture sensing positions, utilizing onlythose measurements which are taken While the presence of the suture issensed both ahead of and behind the diameter sensing position,determining the minimum of all utilized diameter measurements, movingthe suture to a dumping position, discharging the suture from thedumping position, and passing the suture along a path controlled by thesaid minimum diameter measurement to a bin appropriate to said minimummeasurement.

No references cited.

